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diff --git a/Documentation/BK-usage/bk-kernel-howto.txt b/Documentation/BK-usage/bk-kernel-howto.txt deleted file mode 100644 index b7b9075d2910..000000000000 --- a/Documentation/BK-usage/bk-kernel-howto.txt +++ /dev/null @@ -1,283 +0,0 @@ - - Doing the BK Thing, Penguin-Style - - - - -This set of notes is intended mainly for kernel developers, occasional -or full-time, but sysadmins and power users may find parts of it useful -as well. It assumes at least a basic familiarity with CVS, both at a -user level (use on the cmd line) and at a higher level (client-server model). -Due to the author's background, an operation may be described in terms -of CVS, or in terms of how that operation differs from CVS. - -This is -not- intended to be BitKeeper documentation. Always run -"bk help <command>" or in X "bk helptool <command>" for reference -documentation. - - -BitKeeper Concepts ------------------- - -In the true nature of the Internet itself, BitKeeper is a distributed -system. When applied to revision control, this means doing away with -client-server, and changing to a parent-child model... essentially -peer-to-peer. On the developer's end, this also represents a -fundamental disruption in the standard workflow of changes, commits, -and merges. You will need to take a few minutes to think about -how to best work under BitKeeper, and re-optimize things a bit. -In some sense it is a bit radical, because it might described as -tossing changes out into a maelstrom and having them magically -land at the right destination... but I'm getting ahead of myself. - -Let's start with this progression: -Each BitKeeper source tree on disk is a repository unto itself. -Each repository has a parent (except the root/original, of course). -Each repository contains a set of a changesets ("csets"). -Each cset is one or more changed files, bundled together. - -Each tree is a repository, so all changes are checked into the local -tree. When a change is checked in, all modified files are grouped -into a logical unit, the changeset. Internally, BK links these -changesets in a tree, representing various converging and diverging -lines of development. These changesets are the bread and butter of -the BK system. - -After the concept of changesets, the next thing you need to get used -to is having multiple copies of source trees lying around. This -really- -takes some getting used to, for some people. Separate source trees -are the means in BitKeeper by which you delineate parallel lines -of development, both minor and major. What would be branches in -CVS become separate source trees, or "clones" in BitKeeper [heh, -or Star Wars] terminology. - -Clones and changesets are the tools from which most of the power of -BitKeeper is derived. As mentioned earlier, each clone has a parent, -the tree used as the source when the new clone was created. In a -CVS-like setup, the parent would be a remote server on the Internet, -and the child is your local clone of that tree. - -Once you have established a common baseline between two source trees -- -a common parent -- then you can merge changesets between those two -trees with ease. Merging changes into a tree is called a "pull", and -is analagous to 'cvs update'. A pull downloads all the changesets in -the remote tree you do not have, and merges them. Sending changes in -one tree to another tree is called a "push". Push sends all changes -in the local tree the remote does not yet have, and merges them. - -From these concepts come some initial command examples: - -1) bk clone -q http://linux.bkbits.net/linux-2.5 linus-2.5 -Download a 2.5 stock kernel tree, naming it "linus-2.5" in the local dir. -The "-q" disables listing every single file as it is downloaded. - -2) bk clone -ql linus-2.5 alpha-2.5 -Create a separate source tree for the Alpha AXP architecture. -The "-l" uses hard links instead of copying data, since both trees are -on the local disk. You can also replace the above with "bk lclone -q ..." - -You only clone a tree -once-. After cloning the tree lives a long time -on disk, being updating by pushes and pulls. - -3) cd alpha-2.5 ; bk pull http://gkernel.bkbits.net/alpha-2.5 -Download changes in "alpha-2.5" repository which are not present -in the local repository, and merge them into the source tree. - -4) bk -r co -q -Because every tree is a repository, files must be checked out before -they will be in their standard places in the source tree. - -5) bk vi fs/inode.c # example change... - bk citool # checkin, using X tool - bk push bk://gkernel@bkbits.net/alpha-2.5 # upload change -Typical example of a BK sequence that would replace the analagous CVS -situation, - vi fs/inode.c - cvs commit - -As this is just supposed to be a quick BK intro, for more in-depth -tutorials, live working demos, and docs, see http://www.bitkeeper.com/ - - - -BK and Kernel Development Workflow ----------------------------------- -Currently the latest 2.5 tree is available via "bk clone $URL" -and "bk pull $URL" at http://linux.bkbits.net/linux-2.5 -This should change in a few weeks to a kernel.org URL. - - -A big part of using BitKeeper is organizing the various trees you have -on your local disk, and organizing the flow of changes among those -trees, and remote trees. If one were to graph the relationships between -a desired BK setup, you are likely to see a few-many-few graph, like -this: - - linux-2.5 - | - merge-to-linus-2.5 - / | | - / | | - vm-hacks bugfixes filesys personal-hacks - \ | | / - \ | | / - \ | | / - testing-and-validation - -Since a "bk push" sends all changes not in the target tree, and -since a "bk pull" receives all changes not in the source tree, you want -to make sure you are only pushing specific changes to the desired tree, -not all changes from "peer parent" trees. For example, pushing a change -from the testing-and-validation tree would probably be a bad idea, -because it will push all changes from vm-hacks, bugfixes, filesys, and -personal-hacks trees into the target tree. - -One would typically work on only one "theme" at a time, either -vm-hacks or bugfixes or filesys, keeping those changes isolated in -their own tree during development, and only merge the isolated with -other changes when going upstream (to Linus or other maintainers) or -downstream (to your "union" trees, like testing-and-validation above). - -It should be noted that some of this separation is not just recommended -practice, it's actually [for now] -enforced- by BitKeeper. BitKeeper -requires that changesets maintain a certain order, which is the reason -that "bk push" sends all local changesets the remote doesn't have. This -separation may look like a lot of wasted disk space at first, but it -helps when two unrelated changes may "pollute" the same area of code, or -don't follow the same pace of development, or any other of the standard -reasons why one creates a development branch. - -Small development branches (clones) will appear and disappear: - - -------- A --------- B --------- C --------- D ------- - \ / - -----short-term devel branch----- - -While long-term branches will parallel a tree (or trees), with period -merge points. In this first example, we pull from a tree (pulls, -"\") periodically, such as what occurs when tracking changes in a -vendor tree, never pushing changes back up the line: - - -------- A --------- B --------- C --------- D ------- - \ \ \ - ----long-term devel branch----------------- - -And then a more common case in Linux kernel development, a long term -branch with periodic merges back into the tree (pushes, "/"): - - -------- A --------- B --------- C --------- D ------- - \ \ / \ - ----long-term devel branch----------------- - - - - - -Submitting Changes to Linus ---------------------------- -There's a bit of an art, or style, of submitting changes to Linus. -Since Linus's tree is now (you might say) fully integrated into the -distributed BitKeeper system, there are several prerequisites to -properly submitting a BitKeeper change. All these prereq's are just -general cleanliness of BK usage, so as people become experts at BK, feel -free to optimize this process further (assuming Linus agrees, of -course). - - - -0) Make sure your tree was originally cloned from the linux-2.5 tree -created by Linus. If your tree does not have this as its ancestor, it -is impossible to reliably exchange changesets. - - - -1) Pay attention to your commit text. The commit message that -accompanies each changeset you submit will live on forever in history, -and is used by Linus to accurately summarize the changes in each -pre-patch. Remember that there is no context, so - "fix for new scheduler changes" -would be too vague, but - "fix mips64 arch for new scheduler switch_to(), TIF_xxx semantics" -would be much better. - -You can and should use the command "bk comment -C<rev>" to update the -commit text, and improve it after the fact. This is very useful for -development: poor, quick descriptions during development, which get -cleaned up using "bk comment" before issuing the "bk push" to submit the -changes. - - - -2) Include an Internet-available URL for Linus to pull from, such as - - Pull from: http://gkernel.bkbits.net/net-drivers-2.5 - - - -3) Include a summary and "diffstat -p1" of each changeset that will be -downloaded, when Linus issues a "bk pull". The author auto-generates -these summaries using "bk changes -L <parent>", to obtain a listing -of all the pending-to-send changesets, and their commit messages. - -It is important to show Linus what he will be downloading when he issues -a "bk pull", to reduce the time required to sift the changes once they -are downloaded to Linus's local machine. - -IMPORTANT NOTE: One of the features of BK is that your repository does -not have to be up to date, in order for Linus to receive your changes. -It is considered a courtesy to keep your repository fairly recent, to -lessen any potential merge work Linus may need to do. - - -4) Split up your changes. Each maintainer<->Linus situation is likely -to be slightly different here, so take this just as general advice. The -author splits up changes according to "themes" when merging with Linus. -Simultaneous pushes from local development go to special trees which -exist solely to house changes "queued" for Linus. Example of the trees: - - net-drivers-2.5 -- on-going net driver maintenance - vm-2.5 -- VM-related changes - fs-2.5 -- filesystem-related changes - -Linus then has much more freedom for pulling changes. He could (for -example) issue a "bk pull" on vm-2.5 and fs-2.5 trees, to merge their -changes, but hold off net-drivers-2.5 because of a change that needs -more discussion. - -Other maintainers may find that a single linus-pull-from tree is -adequate for passing BK changesets to him. - - - -Frequently Answered Questions ------------------------------ -1) How do I change the e-mail address shown in the changelog? -A. When you run "bk citool" or "bk commit", set environment - variables BK_USER and BK_HOST to the desired username - and host/domain name. - - -2) How do I use tags / get a diff between two kernel versions? -A. Pass the tags Linus uses to 'bk export'. - -ChangeSets are in a forward-progressing order, so it's pretty easy -to get a snapshot starting and ending at any two points in time. -Linus puts tags on each release and pre-release, so you could use -these two examples: - - bk export -tpatch -hdu -rv2.5.4,v2.5.5 | less - # creates patch-2.5.5 essentially - bk export -tpatch -du -rv2.5.5-pre1,v2.5.5 | less - # changes from pre1 to final - -A tag is just an alias for a specific changeset... and since changesets -are ordered, a tag is thus a marker for a specific point in time (or -specific state of the tree). - - -3) Is there an easy way to generate One Big Patch versus mainline, - for my long-lived kernel branch? -A. Yes. This requires BK 3.x, though. - - bk export -tpatch -r`bk repogca bk://linux.bkbits.net/linux-2.5`,+ - |
